Glands and stromal cells will be isolated from endometrial specimens and the distribution of estradiol and progesterone receptors and of various enzymatic activities in these cell types will be determined. Induction of enzymes in endometrial cells in culture will be attempted and related to receptor levels. Among others, the effects of estrogen on peroxidase and ornithine decarboxylase activities and the effects of progestins on estradiol 17 beta dehydrogenase activity will be studied. Comparison of responses of fragments of whole endometrium and of cultures of epithelial and stromal cells will be compared. If responses are obtained with tissue in organ culture but not with the separated cells, cultures of mixed epithelial and stromal cells will be similarly tested since interactions between these cell types may be necessary for responsiveness to hormones. Effects of estradiol on progesterone receptor levels will be studied by incubating proliferative endometrium under organ culture conditions.